Stove for burning bio-mass pellets and grain

A stove, for burning solid particulate bio-fuel, that maintains a continuous pilot burn and operates selectively in updraft and downdraft exhaust modes, comprising in combination:

• a casement peripherally defining an enclosed fire chamber and at least one latchable, hingeably openable access door with a transparent window in the medial portion of the access door;
• a combustion container carried in the lower medial portion of the fire chamber, said combustion container having a fire pot defining three annular vertically spaced arrays of combustion air holes, an annular array of combustion gas holes between upper and medial arrays of combustion air holes, and a fuel conveyor orifice in the lower portion thereof;
• a fuel supply system having a hopper spacedly adjacent the casement with a lower orifice feeding fuel to a first slower conveyor that moves the fuel to a second faster auger conveyor, said second auger conveyor having a cylindrical tube rotatably carrying an auger communicating with the fuel conveyor orifice defined in the fire pot to define a pilot burn area adjacent the fire pot, said second conveyor auger being carried by a shaft carrying an agitator extending into the fire pot to move and admix material in the lower portion of the fire pot;
• a combustion air system having a pilot fire duct to supply combustion air to the pilot burn area defined in the second conveyor tube and three vertically spaced plena on the exterior of the fire pot adjacent each of the annular arrays of air input holes, each said plenum and the pilot fire duct communicating through ducting and valving means to a common combustion air input duct to receive combustion air from the ambient atmosphere externally of the casement;
• an exhaust system having an elongate laterally extending lower exhaust plenum carried on the lower external portion of the casement and communicating with the fire chamber by plural orifices defined in the lower portion of the casement, and an upper exhaust plenum carried on the external surface of the upper portion of the casement vertically above the lower exhaust plenum and communicating to the fire chamber through an updraft orifice defined in the upper portion of the casement, said updraft orifice having a normally closed valve for selective opening, and said lower exhaust plenum communicating with said upper exhaust plenum which communicates with an exhaust channel having an exhaust fan to create a pressure below atmospheric pressure in the exhaust channel to aid exhaustation of combustion gases;
• and
• a control system having a micro-processor and an internal thermocouple and external thermostat, said external thermostat positioned in an area to be heated to institute a full burn cycle responsive to sensed temperature below a predetermined value, and said internal thermocouple carried by the combustion container to open the updraft valve responsive to sensed temperature in the combustion container below a predetermined value.